Mavericks Compatibility Update

* Pulls in Mavericks compatibility stuff from boxen/our-boxen
* Removes old node versions that won't work
* Simplifies the plyfe set up - in particular, added a "dev_environment" manifest
* Comment out `qt` package which will fail - install patched version with `brew install https://raw.github.com/cliffrowley/homebrew/patched_qt_libcpp/Library/Formula/qt.rb --HEAD`. Longer term, may wish to find lower-overhead means of running jasmine specs

This has been tested on a clean mavericks VM, and works great. It may not be quite so easy when installed over an existing installation, but hopefully the idempotence proves useful there.